[RFC PATCH 0/1] dw_mmc: checking card busy with Status register

[RFC PATCH 0/1] dw_mmc: checking card busy with Status register

[Jaehoon Chung]

This RFC patch is applied checking card busy with status register.

In Status register, bit[9] indicate the card busy or not.
So, if we use this bit in status register, we can check the card busy or not.

Maybe, didn't increased the performance, but i think this approach is decreased
the CPU usage.

Anyone, let me know how think about this patch.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
 drivers/mmc/host/dw_mmc.c |   17 +++++++++++++++++
 1 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 87e1f57..882d004 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -647,9 +647,26 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq)
 {
 	struct dw_mci_slot *slot = mmc_priv(mmc);
 	struct dw_mci *host = slot->host;
+	unsigned int timeout = 0x100;
 
 	WARN_ON(slot->mrq);
 
+	while (timeout) {
+		if ((mrq->data && (mrq->data->flags == MMC_DATA_READ)) ||
+			!(mci_readl(host, STATUS) & (1 << 9)))
+			break;
+
+		if (timeout == 0) {
+			dev_err(&host->pdev->dev, "Card is busy!!\n");
+			return;
+		}
+
+		if (!need_resched())
+			usleep_range(10, 50);
+
+		timeout--;
+	}
+
 	if (!test_bit(DW_MMC_CARD_PRESENT, &slot->flags)) {
 		mrq->cmd->error = -ENOMEDIUM;
 		mmc_request_done(mmc, mrq);

Re: [RFC PATCH 0/1] dw_mmc: checking card busy with Status register

[Will Newton]

On Fri, Mar 25, 2011 at 6:00 AM, Jaehoon Chung <jh80.chung@samsung.com> wrote:
> This RFC patch is applied checking card busy with status register.
>
> In Status register, bit[9] indicate the card busy or not.
> So, if we use this bit in status register, we can check the card busy or not.
>
> Maybe, didn't increased the performance, but i think this approach is decreased
> the CPU usage.
>
> Anyone, let me know how think about this patch.

Do you have any numbers to report how this patch altered CPU usage or
card throughput for you? e.g. oprofile output or dd performance